Classification and Naming

Targeted cancer agents are broadly classified as either monoclonal antibodies or small molecules.

Therapeutic monoclonal antibodies target specific antigens found on the cell surface, such as transmembrane receptors or extracellular growth factors. In some cases, monoclonal antibodies are conjugated to radio-isotopes or toxins to allow specific delivery of these cytotoxic agents to the intended cancer cell target.

Small molecules can penetrate the cell membrane to interact with targets inside a cell. Small molecules are usually designed to interfere with the enzymatic activity of the target protein.

As with any drug, targeted cancer therapies typically have several different names. One or more names is used to designate the chemical compound during development; if successful, the drug receives a generic name and then a brand name used by the pharmaceutical company for marketing. For example, the small molecule STI-571 became known as imatinib (generic name) and is marketed by Novartis under the brand name Gleevec™.

The name of a targeted agent provides clues to the type of agent and its cellular target. 

Monoclonal antibodies end with the stem "-mab" (monoclonal antibody). Small molecules end with the stem "-ib" (indicating that the agent has protein inhibitory properties). Monoclonal antibodies have an additional substem designating the source of the compound, e.g., "-ximab" for chimeric human-mouse antibodies, "-zumab" for humanized mouse antibodies, and "-mumab" for fully human antibodies. Both monoclonal antibodies and small molecules contain an additional stem in the middle of the name describing the molecule’s target; examples for monoclonal antibodies include "-ci-" for a circulatory system target and "-tu-" for a tumor target, while examples for small molecules include "-tin-" for tyrosine kinase inhibitors and "-zom-" for proteasome inhibitors. At the beginning of the generic name is a prefix that is unique for each agent. Some examples include:

The FDA has approved multiple targeted drug cancer therapies, and many more are being studied in clinical trials either alone or in combination with other treatments. A partial list of currently approved targeted therapies for solid malignancies and their molecular targets is provided below.